Device for removing the noxious and aromatic substances from an air flow fed into the interior of a vehicle

ABSTRACT

A device for removing noxious and aromatic matter from a conducted air flow into the interior of a vehicle comprises an air conduction housing with a reactor containing an adsorbent. To attain consistently good adsorption and absorption power with small amounts of adsorbing and absorbing material, the air conduction housing is designed with two separate parallel air flow channels, in each of which there is a reactor in the form of a flat wall. An adsorption air flow acts upon the adsorbent in one air flow channel and a desorption air flow acts upon the adsorbent in the other air flow channel, the direction of air flow into the reactor in the adsorption operation being opposite that in the desorption operation.

BACKGROUND OF THE INVENTION

The invention relates to a device for removing the noxious and aromaticsubstances from an air flow fed into the interior of a vehicle. Thedevice comprises an air feed housing in which at least one reactor isdisposed that absorbs the noxious and aromatic substances.

DE 35 32 463 A1 discloses an air-conditioning system for a motor vehiclein which a dust filter and an odor filter are disposed in an air feedduct. Such odor filters comprise materials which absorb the aromaticsubstances because of their surface structure. Since the adsorptionpower of such filters is limited, the adsorption power decreases as timeprogresses and some of the substances deposited are liberated again andfed again into the interior of the vehicle by the air flow. After aspecified operating time, these filter elements have to be replaced. Sothat the servicing intervals do not become too short, such filters haveto be of appropriately large design in regard to the volume and/or thepacking density, which is disadvantageous in regard to the installationspace required or the pressure loss which occurs. In addition, only afew types of odorous or noxious substances are dealt with by the knownfilters.

DE 35 17 105 C1 describes a method for continuously removing noxioussubstances from a gas flow. For this purpose, a drum is provided whichis filled with an absorbent, in which the gas to be purified entersthrough a pipe and to which there are connected two pipes through whichthe gas leaves. No defined air flows are formed in the drum, with theresult that the exposure of the individual zones is essentiallydependent on the flow resistances within the absorbent and at theoutgoing pipes. Because of the bulk density in the drum, high pressurelosses are produced, with the result that a high expenditure of energyis necessary to generate the gas flow. In addition, to desorb thereactor material, the gas flow component which has taken up the desorbednoxious substances has to be fed through the entire reactor to theappropriate outgoing pipe in the known arrangement.

DE 40 23 995 C2 discloses a device for fresh-air and interior-airpurification in motor vehicles by means of a photocatalyst which isirradiated with photons and has a semiconductor base. To operate such adevice, a mercury-vapor lamp which is attached using spring means to thecatalyst bed fixed to the vehicle is required as radiation source.

DE 35 45 664 A1 describes a ventilation device for the cabin of anagricultural vehicle which comprises a fan and a plurality of filters.In this case, a first filter is designed as dust filter and a secondfilter as liquid trap. The third filter is a reactor for removing toxicsubstances in the intake air. Said filter is designed as a flat wall andis disposed in an air flow path upstream of the driver's cabin. Theair-flow direction through the reactor can be reversed with the aid ofmultiway valves, one of the flow directions being provided foradsorption operation and the other flow direction for the desorptionoperation of the reactor.

SUMMARY OF THE INVENTION

The object of invention is to provide a device for removing the noxiousand aromatic substances, which achieves a high degree of purity of theair fed into the interior of the vehicle and in the case of whichcontinuous and maintenance-free operation is possible.

The essential advantages of the invention are to be seen in the factthat, of the adsorber material present in total, some of it is alwaysdisposed in the air flow to be purified as adsorber or absorber, whilethe rest is purified by means of a desorption air flow. In this way, ahigh adsorption power or absorption power is always provided,accompanied by completely maintenance-free operation. The total quantityof the adsorber material can be kept small since regenerated material isalways available, and increasing contamination with operating time doesnot occur. The separate air flow paths result in a defined exposure ofthe reactor material and the design as flat wall element has theadvantage that the flow resistance or the pressure drop is kept low. Theopposite air-flow direction achieves the result that the section of thereactor having the greatest contamination is adjacent to the airdischarge opening.

According to a preferred embodiment of the invention, the air flow pathsare formed by a common main air chamber and two separate subsidiary airchambers, and each of the reactors is disposed between the main airchamber and one of the subsidiary air chambers. Air flow controlelements are provided in the main air chamber and the subsidiary airchambers, by means of which air flow control elements the reactors canbe alternately switched over from adsorption operation to desorptionoperation and vice versa. In this design, the reactor which is inadsorption operation is connected on the downstream side to the interiorof the vehicle, and the reactor which is in desorption operation isconnected on the downstream side to the outside of the vehicle. Such anarrangement has the advantage that the reactors are disposed in astationary manner, the air flows being fed through the reactorsalternately in accordance with specified cycles by means of the air flowcontrol elements.

As an alternative to this, it is, however, also possible that a housingis provided which comprises a rotating reactor through which the airflow paths are fed in chambers of the housing, sectors of the reactorbeing moved from the adsorption air flow chamber into the desorption airflow chamber and vice versa. The air flow control elements can beomitted in the arrangement comprising a rotating reactor. A suitabledrive for the reactor is, however, necessary for this purpose. Such areactor is preferably moved in steps in accordance with a specified timecycle, in which connection the step angle may be a maximum of 180°, butpreferably<90°. As an alternative to this, the reactor may be rotatedcontinuously.

The desorption action is increased in the case of some adsorbermaterials if heat is supplied. It is therefore advantageous that, todesorb the adsorbent, a heating device, in particular a PTC heater or aradiator with water flowing through it, is disposed upstream of thereactor. Since the heating device is disposed upstream of the reactorand heats the desorption air flow, the desorption takes placeadiabatically. At least one fan is provided to generate the necessaryair flow, the total air flow leaving the fan being divided up into adesorption air flow and an adsorption air flow by suitable design. Itis, however, also possible to provide a separate fan for the desorptionair flow. To avoid a contamination of the absorber material byparticles, particle filters of conventional design may be disposed inthe air path upstream of the reactors.

Suitable as adsorber materials are active carbon, zeolite, aluminumoxide and silica gel. At the same time, it is possible that the reactorcomprises a combination or mixture of at least two of these materials.The combination or mixing of different adsorbers has the advantage thatthe spectrum of the absorbed noxious and aromatic substances isincreased. If certain adsorber materials are not suitable for mixingbecause of their structure, the combination of the adsorption materialscan be achieved in that the various materials are disposed in layersextending transversely with respect to the air flow opening.

In particular, in reactors which comprise at least in part zeolite orsilica gel, moisture is removed from the air flow in addition to theremoval of noxious and aromatic substances, with the result that notonly purified, but also dry air is fed into the interior of the vehicle.The moisture is also expelled from the reactor with the desorption airflow in the desorption phase.

The reactor can be designed as a monolith or bed of adsorber materials.It is also possible, however, to deposit the adsorption material on asupport structure in the form of a coating, in which connection thesupport structure may be a heat-transfer plastic foam or a heat-transferlattice. So that viruses and microorganisms are also removed from theair flow in addition to noxious and aromatic substances, in addition tothe adsorber materials, areas are provided which have a copper-oxide ornoble-metal coating. For the purpose of accelerated regeneration of thereactor in the case of heavy contamination of the adsorption material,it is expedient to provide a device for flushing the reactor by means ofsteam shock or a flushing gas.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the device for removing the noxious andaromatic substances are explained in greater detail below by referenceto the drawings. In the drawing:

FIG. 1 shows a diagrammatic representation of an air purification devicefor a motor vehicle,

FIG. 2 shows the device according to FIG. 1 in a second operatingposition,

FIG. 3 shows an air purification device having a desorption air streamfed in separately,

FIG. 4 shows the device according to FIG. 3 in a second operatingposition, and

FIG. 5 shows a rotating reactor.

The device 1 shown in FIGS. 1 and 2 for purifying an air stream 2 fedinto the interior of a vehicle comprises two reactors 4 and 5 which aredisposed in a housing 3, which are disposed in parallel to one anotherand between which a common main air chamber 6 is formed.

The reactors 4, 5 are designed as flat wall elements, and eachdelineates by means of the other side a subsidiary air chambers 7 and 8which extend in parallel to the longitudinal direction of the reactors.Each reactor 4, 5 forms an air-permeable wall between the subsidiary airchambers 7, 8 and the main air chamber 6. The main air chamber 6 and thesubsidiary air chambers 7, 8 are open at their ends adjacent to an airinlet chamber 9. A heating device 10 for heating the air flow enteringthe main air chamber is provided at the inlet side of the main airchamber 6.

Disposed in each subsidiary air chamber 7, 8 and in the main air chamber6 is an air control element 11, 12, 13 which is designed as a valve andwhich extends diagonally in the respective chamber 6, 7, 8 and can beswivelled about a swivelling axis S₁, S₂, S₃ in the center of the valve,with the result that the air flow control elements can be switchedbetween the end positions determined by the diagonals of the airchambers 6, 7, 8. All the air flow control elements 11, 12, 13 areactuated simultaneously, preferably by a common drive. The air flowcontrol valve 11 in the main air chamber 6 divides said chamber in eachof the two possible positions into a front region 6' and a rear region6". Connected to an opening 14 in the region 6" of the main air chamber6 is an air duct 15, which is not shown in the drawing and leads to theinterior of the vehicle.

In the subsidiary air chambers 7 and 8, air outlet openings 16, 17 areprovided which are disposed at the ends situated remotely from the airinlet chamber and to which the air outlet ducts 16' and 17' areconnected.

The air outlet openings 16, 17 can be closed depending on the positionof the air flow control elements 12, 13, one of the air outlet openingsalways being closed and the other open.

Disposed on the housing 3 upstream of the air inlet chamber 9 is a fan18 having a radial blower wheel 19 which sucks in air in accordance withthe arrow 20 (this may be, for example, air removed from the interior ofthe vehicle) and generates an air flow through a diffuser 21 into theair inlet chamber 9. This air flow is divided up into an adsorption airflow 22 and a desorption air flow 23, which first flows through theheating device 10. Because of the position of the air flow controlelements 11, 12 and 13 according to FIG. 1, the adsorption air flow 22is fed through the reactor 4 and purified therein, said purificationbeing an adsorption and/or absorption of noxious and aromaticsubstances. The adsorption air flow discharges from the reactor 4 intothe region 6" of the main air chamber 6 and leaves the latter throughthe opening 14 and the air duct 15 as purified air flow 2, which is fedinto the interior of the vehicle.

The desorption air flow 23 enters the region 6' of the main air chamber6, arriving from the heating device 10, and is fed through the reactor 5because of the position of the air flow control element 11 and picks uptherein the noxious and odorous substances deposited on the surface ofthe adsorber material. The desorption air flow leaving the reactor 5discharges through the outlet air opening 17 disposed in the subsidiaryair chamber 8 and is discharged into the surrounding air. If the airflow control elements 11, 12 and 13 are set to the second possibleposition, as is shown in FIG. 2, because of the position of the air flowcontrol elements 11, 12 and 13, the reactor 5 serves to purify theadsorption air stream 22 which enters the region 6" of the main airchamber 6 from the subsidiary air chamber 8 and is fed from there to theinterior of the vehicle as purified air flow 2. At the same time, thedesorption air flow 23 is fed through the reactor 4 into the subsidiaryair chamber 7 and discharges through the air outlet opening 16 and theair outlet duct 16'.

The device shown in FIGS. 3 and 4 differs from the one described abovein that the subsidiary air chambers 7 and 8 are not connected to the airinlet chamber 9 but are exposed to a separate air flow. The entirearrangement is disposed in an air feed duct 25 into which is fed airfrom the interior of the vehicle in accordance with arrows 26. Aparticle filter 27 is provided to remove coarse contaminants in theairstream, so that the adsorption air stream does not load the reactor 4or 5 with dirt. An air duct 29 connected to the outside of the vehicleleads to the intake region of a fan 30, which serves solely to generatethe desorption air flow 23. It is also possible to dispose a particlefilter in the air duct 29 so that the dirt present in the outside airdoes not load the reactor. In other respects, the operation of thedevice is the same as that described in connection with FIGS. 1 and 2,so that reference is made to the details relating to them.

FIG. 5 shows a rotating reactor 32 which can be used instead of thestationary reactors 4 and 5 shown in FIGS. 3 and 4. The reactor 32,which has the shape of a disk, is disposed in a housing 33 which issubdivided into a chamber 35 for the adsorption air flow and a chamber36 for the desorption air flow. In each chamber 35 and 36, the reactorforms an air-permeable flat wall element extending transversely withrespect to the air flow direction. The reactor has a drive shaft 37 bymeans of which the reactor is moved around the axis of rotation 38 inthe direction of the arrow 39. The adsorption air stream 22 enters thechamber through a connecting pipe piece 41 and is purified by a reactorsection disposed in said chamber in order then to be fed into theinterior of the vehicle through an air feed duct 34 as purified air flow2. The desorption air flow 23 is first fed through the heating device 10and then through a connecting pipe piece 40 of the chamber 36 for thedesorption air flow. The noxious substances deposited in the adsorptionmaterial are picked up from the reactor section disposed in said chamber36 and fed through an outlet air duct 42 into the open air.

The devices described above are able to pick up various noxious andaromatic substances depending on the type of adsorber material, themixture or combination of various materials substantially increasing thespectrum of the types of substances eliminated. As examples of thesubstances to be removed mention may be made, in particular, ofhydrocarbons, such as ether and benzenes, and also alcohols, hydrogensulfides, amines, ammonia, nicotine, carboxylic acid, halides andmethylene chloride. In addition, it should be specially emphasized thatall the exhaust-gas constituents which vehicles discharge into the airare also filtered out by the device, as are their reaction products, ofwhich mention should be made, in particular, of ozone. The purificationof the air fed into the interior of the vehicle is an importantcontribution to the well-being of the vehicle passengers and, inaddition, increases traffic safety since, because of the removal ofmoisture from the absorption air flow, dry air is fed into the interiorof the vehicle and consequently condensation on the windows is avoided.

We claim:
 1. A device for removing noxious and aromatic substances froman air flow fed into the interior of a motor vehicle, comprisingan airfeed housing of a size and configuration to fit inside of the motorvehicle, said air feed housing defining first and second separate andparallel air flow paths and having an air intake and a first air outletadapted to deliver air to the interior of the motor vehicle; at leastone reactor positioned in each of the air flow paths, said reactor beingdesigned as a generally planar bed member and being comprised of anadsorbent material that adsorbs both noxious and aromatic substancescontained in the air; and a flow control device for alternatelysubjecting the adsorbent material in the first air flow path to anadsorption air flow and the adsorbent material in the second air flowpath to a desorption air flow, wherein the air flow direction in theadsorbent material in the first and second air flow paths are oppositeduring adsorption and during desorption, wherein said air feed housingcomprises a common main air chamber and two subsidiary air chambers,wherein a reactor is disposed between the main air chamber and each oneof the subsidiary air chambers and wherein said flow control deviceincludes air flow control elements provided in the main air chamber andthe subsidiary air chambers for alternatively switching over betweenadsorption operation and desorption operation, the reactor which is inadsorption operation communicating on the downstream side with saidfirst air outlet to the vehicle interior, and the reactor which is indesorption operation communicating on the downstream side to a secondair outlet in said air feed housing that is adapted to deliver air tothe outside of the vehicle.
 2. A device according to claim 1, furthercomprising a heating device disposed upstream of the reactor.
 3. Adevice according to claim 2, wherein said heating device comprises a PTCheater or a radiator with water flowing through it.
 4. A deviceaccording to claim 1, further comprising a fan connected to the airintake of said air feed housing.
 5. A device according to claim 4,wherein said air intake of said air feed housing communicates with theinterior of the vehicle for withdrawing exhaust air therefrom.
 6. Adevice according to claim 1, further comprising a fan connected to onlyone of said first or second air flow paths, said fan being connected toa source of air on the outside of the vehicle, and said air flow pathcontaining said fan being connected solely to said main air chamber, forsupplying desorption air flow exclusively from said outside air sourcevia said fan.
 7. A device according claim 1, further comprising aparticle filter provided in at least one of said flow paths.
 8. A deviceaccording claim 1, wherein the reactor is comprised of at least oneadsorbent material selected from the group consisting of active carbon,zeolite, aluminum oxide and silica gel.
 9. A device according to claim8, wherein the reactor is comprised of a combination or mixture of atleast two of said adsorbent materials.
 10. A device according to claim9, wherein the reactor comprises a combination of at least twomaterials, wherein each material is disposed in a separate layerextending transversely with respect to the air flow direction.
 11. Adevice according to claim 1, wherein the reactor comprises a monolith orbed of adsorbent material.
 12. A device according to claim 1, whereinthe reactor comprises an adsorbent material coating on a substrateselected from a heat transfer medium, plastic foam or lattice.
 13. Adevice according to claim 1, further comprising in conjunction with saidreactor at least one area having a copper-oxide or noble-metal coating.14. A device according to claim 1, further comprising a device forflushing the reactor by means of steam shock or a flushing gas.
 15. Adevice for removing noxious and aromatic substances from an air flow fedinto the interior of a motor vehicle, comprisingan air feed housing of asize and configuration to fit inside of the motor vehicle, said air feedhousing defining first and second separate and parallel air flow pathsand having an air intake and a first air outlet adapted to deliver airto the interior of the motor vehicle; at least one reactor positioned ineach of the air flow paths, said reactor being designed as a generallyplanar bed member and being comprised of an adsorbent material thatadsorbs both noxious and aromatic substances contained in the air; and aflow control device for alternately subjecting the adsorbent material inthe first air flow path to an adsorption air flow and the adsorbentmaterial in the second air flow path to a desorption air flow, whereinthe air flow direction in the adsorbent material in the first and secondair flow paths are opposite during adsorption and during desorption,wherein said at least one reactor comprises a single bed member, andsaid flow control device comprises a drive to rotate said bed membersuch that alternate areas of said bed member are alternately positionedin the first and second air flow paths.
 16. A device according to claim15, wherein said drive is adapted to rotate said bed member in steps inaccordance with specified time cycles.
 17. A device according to claim15, wherein said drive is adapted to continuously rotate said bedmember.
 18. A device according claim 15, further comprising a particlefilter provided in at least one of said flow paths.
 19. A deviceaccording claim 15, wherein the reactor is comprised of at least oneadsorbent material selected from the group consisting of active carbon,zeolite, aluminum oxide and silica gel.
 20. A device according to claim19, wherein the reactor is comprised of a combination or mixture of atleast two of said adsorbent materials.
 21. A device according to claim20, wherein the reactor comprises a combination of at least twomaterials, wherein each material is disposed in a separate layerextending transversely with respect to the air flow direction.
 22. Adevice according to claim 15, wherein the reactor comprises a monolithor bed of adsorbent material.
 23. A device according to claim 15,wherein the reactor comprises an adsorbent material coating on asubstrate selected from a heat transfer medium, plastic foam or lattice.24. A device according to claim 15, further comprising in conjunctionwith said reactor at least one area having a copper-oxide or noble-metalcoating.
 25. In a motor vehicle, a device for removing noxious andaromatic substances from an air flow fed into the interior of a motorvehicle, comprisingan air feed housing of a size and configuration tofit inside of the motor vehicle, said air feed housing defining firstand second separate and parallel air flow paths and having an air intakeand a first air outlet adapted to deliver air to the interior of themotor vehicle; a fan connected to the air intake of said air feedhousing; at least one reactor positioned in each of the air flow paths,said reactor being designed as a generally planar bed member and beingcomprised of a combination of at least two adsorbent materials selectedsuch that the reactor adsorbs both noxious and aromatic substancescontained in the air; and flow control means for alternately subjectingthe adsorbent material in the first air flow path to an adsorption airflow and the adsorbent material in the second air flow path to adesorption air flow, wherein the air flow direction in the adsorbentmaterial in the first and second air flow paths are opposite duringadsorption and during desorption.
 26. A device according to claim 25,wherein each adsorbent material in said reactor is disposed in aseparate layer extending transversely with respect to the air flowdirection.